Core tube placement and retrieval

ABSTRACT

There is disclosed a drill string having an annular core bit on the end thereof inside of which is placed a core tube for receiving cylindrical cores cut by the bit. The core tube is positioned in core receiving relation to the bit merely by pumping the core tube through the drill string. The core tube is retrieved from the bore hole by pumping a core tube conditioning element through the drill string which engages the core tube and manipulates a latching mechanism thereof to disengage the core tube from the drill string. The core tube is then pumped out of the drill string by pumping into the annulus between the drill string and the bore hole.

United States Patent 1 1 Fulford CORE TUBE PLACEMENT AND 3 2/ 970 M75/60 v 3,543,87 l l artinsen.... RETRIE AL 3,667,558 6/l972 Lambotl75/236X [75] Inventor: Emory Eugene Fulford, Austinvrlle, i Va. PrimaryExaminer-David H. Brown [73] Assignee: The New Jersey Zinc C0,,Attorney, Agennor Firm.-Colto'n & Stone,- Inc.

Austinville, Va. A 221 Filed: Apr. 19, 1974 AB TRA 2] A N 462,447 Thereis disclosed a drillvstring having an annular core I 1 pp 0 bit on theend thereof inside of which is placed a core tube for receivingcylindrical cores cut by the bit. The Y Cl 175/236, 175/239, 75/247 coretube is positioned in core receiving relation to I [5 the bit merely thecore tube through he Field of Search 249, 3 drill string. The core tubeis retrieved from the bore 175/246, 247; 166/1 156 hole by pumpinga-core tube conditioning element through the drill string which engagesthe core tube References Cited and manipulates alatching mechanismthereof to dis- UNITED STATES PATENTS engage the core tube from thedrill string. The} core 473.910 5/1892 Bullock 175/60 tube is Pumped 1"0f the drill String by P g 2145470 1 1939 into the annulus between thedrill string and the-bore 2.220.554 ll/l940 hole. 3,120,283 2/1964 9Cla'6 in F 3.333.647 8/1967 Kar1ch et =11. 175/247 34/1 I [40 Dr 1; B

2 f 1 ?-13s 5 -|3o 4408 a a] (5 l 4114 In i ""0 94c 9s BO 1 122 a, i v3. ix: 76

' 34 lg/98 Q I 9o k b e A 1 51 Apr. 1, 1975 9/1967 Lindelofihi...

FATENTEDAPR 1157s 3,874,466

FIG. IB FIG. IA

PATENTEDAPR' 1 ms SHEET 2 [IF 2 FIG.3

FIG.4

1 CORE TUBE PLACEMENT AND RETRIEVAL Coring devices are well known andwidely used both in oil exploration activities and in hard rock miningexploration activities. These applications for core drilling have muchin common with several distinct differences. One difference is that coredrilling in the oilfield is typically done at substantial depths beneaththe surface whereas in hard rock exploration, the distance from the corebit to the drilling machine is normally substantially less. Anothersubstantial distinction is that oil field applications almostuniversally involve drilling downwardly whereas in many hard rocksituations, either horizontal or upward core drilling is conducted. Uponanalysis, it will be apparent that up" drilling or horizontal drillingrequires tool modification since gravity cannot be employed to place thecore tube adjacent the bit.

This invention provides a core tube providing substantial flexibility inplacement and retrieval thereof. Specifically, the core tube of thisinvention may be pumped in and pumped out of either up, horizontal ordown holes. The core tube can likewise be pumped in and pulled out, asby a wire line, of either up, horizontal or down holes.

The provision of pump in pump out core tubes is known in the prior artas illustrated in U.S. Pat. Nos. 2.073.263; 2,145,170; 2,220,554;2,277,989; and 3,066,748. Of some interest is the disclosure in U.S.Pat. No. 3.543.870. Of more general interest are the disclosures in U.S.Pat. Nos. 473,910; 3,120,282; 3,120,283; 3,225,845; and 3,333,647.

The disclosures in the prior art which provide pump in pump out coretubes usually have one or both of the following disadvantages: l) thedevices employ valving structure which is subject to obstruction and/orerosion by well cuttings or drilling fluid; and (2) the latch mechanismis not positively locked but can be disengaged merely by pressuredifferentials.

It is accordingly an object of this invention to provide an improvedpumpable core tube for use in the core drilling of up, horizontal ordown holes.

IN THE DRAWINGS,

FIGS. 1A, 1B and 1C are partial longitudinal cross sectional views of adrilling apparatus constructed in accordance with the principles of thisinvention, which when longitudinally aligned along the lines A-A and BBillustrate the entire drilling apparatus of this invention;

FIG. 2 is a view similar to FIG. 1A illustrating an unlatched positionbetween the core tube and the surrounding drill string;

FIG. 3 is a horizontal cross sectional view of the del vice of FIG. 1Ataken substantially along line 3-3 thereof as viewed in the directionindicated by the arrow; and

FIG. 4 is a side elevational view, partly in section, illustrating anovershot which is used to manipulate the latching mechanism from theposition shown in FIG. 1A to the position shown in FIG. 2.

Referring to FIGS. 1 and 2, there is illustrated a core drilling device10 comprising a plurality of threadably connected joints of drill pipe12, a landing nipple 14, and one or more pup joints l6, l8 constitutinga drill string 20 having on one end thereof an annular or core bit 22.The core drilling device 10 also comprises a core tube 24 which islatched to the drill string 20 in the position of FIG. 1 in corereceiving relation relative to the bit 22. As will be more fullyexplained hereinafter; the core tube 24 may be withdrawn from the drillstring 20 in order to recover cores cut by the bit 22. After the coretube 24 has been removed from the drill string and the cores removedtherefrom, the core tube 24 is reinserted into the drill string foradditional drilling.

As will be apparent to those skilled in the art, the important functionsof that portion of the drilling device 10 illustrated in FIGS. 1B and 1Care to receive and retain the core cut by the bit 22 with minimum damagethereto, to break the core so cut during or previous to withdrawal ofthe core tube 24 from adjacent the bit end of the drill string 20 and toallow circulation of drilling fluids through and around the drillstring. Although that portion of the drilling device 10 illustrated inFIGS. 1B and 1C may be of any suitable design, for purposes of brevitythis portion of the drilling device 10 is illustrated as a Model AQ-Ucoreing device made by the Longyear Company.

It will suffice for present purposes to state that the core tube 24includes an inner core receiver 26 having core lifters 28 adjacent thebit and stabilizers 30 intermediate the core receiver 26 for centeringthe receiver 26. Adjacent the upper end of the core receiver 26 is agrease fitting 32 for injecting grease into a spring and bearingassembly 34. Above the spring and bearing assembly 34 is a dual shut-offvalve arrangement'36 comprised of a plurality of rubber washers 38, 40and a pair of metallic washers 42, 44. A nut 46 above the valvearrangement 36 allows pretensioning of the washers 38, 40 in aconventional manner.

Above the valve arrangement 36 is an adjusting device 48 which allowsthe maintenance of an appropriate gap between the end of the corereceiver 26 and the bit 22 as shown in FIG. 1C. The adjusting device 48comprises a nut 50 threaded on a rod 52.

Above the adjusting device 48 is a valve cage and hanger assembly 54.The assembly 54 comprises a lower end 56 threaded on' to the rod 52 andan upper end providing a shoulder58 for support on an insert 60 receivedbetween the mal eand female couplings of the drill string 20. The coretube 24 is accordingly restrained against further movement toward thebit 22 by the cooperation of the shoulder 58 and insert 60.

The assembly 54 provides an axial passage 62 com-- municatin g with aplurality of passages 64 above the insert 60 and a plurality of;passages 66 below the insert 60. The passages 62, 64, ;6 6 accordinglyprovide a bypass through the assembly ;54 which is closed by a ballcheck valve 68 biased in the closed direction by a spring 70. An O-ringseal 72 provides a seal between the assembly 54 and the ,insert 60.

Those skilled in the artiwill recognize that portion of the drillingdevice 10 heretofore described as being-a Longyear Model AQ-U coredrilling device. For a more detailed explanation thereof, reference ismade to publications of the Longyear Company.

Referring to FIGS. 1A and 2, there are illustrated the principalfeatures of this invention. The core tube 24 comprises a tubular shell74 integral with or attached to the valve cage and hangar assembly 54.Inside the shell 74 are a latch mechanism 76 and a latch actuatingassembly 78.

The latch mechanism 76 comprises a pair of substantially identical latchelements 80, 82 mounted for pivo .tal movement about a common pin 84 formovementtends throug'h the shell 74 so that the forward nose of;

latch elements 80, 82 rest in an anvil 88. A pair of pins 90 secure theanvil 88 to the shell 74. The latch elements 80,82 respectively comprisean upwardly facing latch shoulder 92, 94 for abutting a downwardlyfacing shoulder 96 provided by the configuration of the male connectionof the joint 12 and an enlarged groove 98 provided by the landing nipple14. The latch elements 80, 82 each provide an upwardly extendingprojection 100 providingan inclined camming surface 102 for moving andholding thelatch elements 80, 82 inthe unlatched position of FIG. 2'andan abutment 104 for of the elements 80, 82. So long as the member 106 ispositively held in the position of FIG. 2 against the bias of thespring120, the latch elements 80, 82 are posi- -.tively prevented frommoving toward a latched position. v

The member 106 also includes a second section 128 comprised of acylindrical valve body 130 connected to the first section 108 and"having a plurality of inclined passages 132 opening through the side ofthe valve body 130. The valve body 130 and the inside of the tuholdingthe latch elements 80, 82v in the latched position of FIG. 1A. 'As willbe more fully pointed out hereinaft'er', the latch elements 80, 82 arepositively mechanically held in the latched position which preventsmovement of the core tube 24 relative to the drill string in a directionaway from the'bit 22.

The-latch actuating assembly 78 constitutes an important part of thisinvention and includes an actuating member 106 extending axially of thecore tube.24. The merriber l0 6t includes a first generally cylindricalsection 108 reciprocably slidably received in aligned axial openingsafforded by a pair of bearing blocks 110, 112 which are secured to theshell 74, as by the provision of suitable set screws 114, 116. The firstsection 108 includes an enlargement 118 thereon positioned between thebearing blocks 110, 112. As seen in FIG. 1A, the block 110 andenlargement 118 cooperate to provide a first limit of reciprocablemovement of the memher 100 at a first latched position of the latchelements 82, 84. A suitable spring 120 is disposed between theenlargement 118 and the block 112 for normally biasing-themember 106toward the first latched position illustrated in FIG. 1A.

Affix'ed to one end of the section 108 is a lug or protuberance 122which acts, in the first position of the member l06,'to engage theabutments 104 of the latch elements 80, 82'to prevent inward pivotalmovement thereofout'of latching engagement with the drill string 20. Asshown in FIG. 1A. the lug 122 comes into its blocking position relativeto the abutments 104 as the enlargement 1 18 approaches its first limitin'engagement'with the bearing block 110. As will be more fullyapparent; hereinafter, the lug 122 positively prevents movement ofthelatch elements 80, 82 toward the unlatched position thereof.

Positioned on thefirst section 108 between the enlargement 1l8 and thelug 122 is a camming element ,124 located below the bearing block 112.The camming element 124 provides'an internal generallyfrustoconical.camm'ing'surface 126 adapted to engage the cammingsurfaces 102 of the latch elements 80, 82

upon downward movement of the member 106. As illustrated in FIG. 2, thecamming element 124 moves the latch elements 80, 82 to the unlatchedposition thereof in response .to movement of the member 106 toward thebit 22. It will be seen that the limit of movement of the member 106toward the bit 22 is determined by engagement of the camming member '124with the latch elements 80, 82 rather than 'coaction of the enlargement118 and the spring 120.In any event, there is provided a second limit ofreciprocable movement of the member106 at a second unlatched positionbular shell 74 are sized to provide a relatively close mating fitthroughout the limits of movement of the valve body 130. i

As is apparent from F IG. 1A, each of the, valve passages 132 registerswith a passage 138 in the tubular shell 74 when the latch actuatingmechanism 78 is in its latched position. It will accordingly be apparentthat drilling fluid pumped down the drill string as suggested by thearrow 140 flows through the passages 134, 132, 138 into the annulusbetween the core tube 24 and the drill string 20 as suggested by thearrows 142.

Threaded onto the top of the tubular shell 74 is a collar or couplingmember 144 providing a surface 146 abutting the top of the valve body130 at the latched position of the mechanism 78. A sealing washer 148 iscaptivated between the collar 144 and a nut 150 for sealing against theinside of the drill string 20. For purposes more fully explainedhereinafter, a fishing neck or spear point 152 is threaded onto the topof the collar 144.

It will be apparent that the normal position of the latch actuatingmechanism 78 is the latched position of FIG. 1A because ofthe biasafforded by the spring 120. In order to place the core tube 24 in thedrilling position illustrated in FIG. 1 from the floor of a drillingmachine, the operator presses on the sleeve 136 to collapse the spring120 and thereby retract the latch elements 80, 82 into the configurationshown in FIG. 2.

. The core tube 24 is then inserted into the open collar of the drillpipe joint exposed at the drilling machine until the latch elements 80,82 are inside this joint. The inner diameter of the drill pipe 12 issmall enough to prevent the latch elements 80, 82 from opening asufficient distance to allow the lug 122 to enter between the abutments104. v

The core tube 24 is pushed completely into the joint of drill pipeexposed at the drilling machine and a cap is threaded onto this joint.Suitable pressure connections are afforded by the cap so that water orother drilling fluid may be pumped into the drill string 20. Pumpinginto the cap acts against the seal 148 to pump the core tube 24 throughthe drill string 20 toward the bit 22. As the core tube 24 approachesthe bit end of the drill string 20, the shoulder 58 engages the insert60 and prevents further movement of the core tube 24 toward the bit22..The spacing between the insert 60 and the landing nipple 14 is suchthat the latch elements 80, 82 are aligned with the shoulder 96. As thelatch elements 80, 82 become free to move about their pivot pin As thedrill string is rotatedand advanced, the core cut by the bit 22 entersthe .core receiver 26 thereby tending to move the coreqtube 24 away fromthe bit 22 which is prevented-by, engagement of the shoulders 92, 94,96.

After a core of sufficient length has been cut, it is of coursenecessary to retrieve the core tube'24 so that the core may be removedfrom the receiver 26 and examined. Accordingly, circulation of drillingfluid down the drill string 20 is stopped and the circulating headremoved from the joint of drill pipe at the drilling machine. Anovershot 154 as shown in FIG. 4 is placed into the drill string 20.

The overshot 154 comprises abody 1.56 having a pair of latch arms 158,160 mounted for rotation about a pivot pin 162. The arms 158, 160provide grappling shoulders 164, 166 respectively for latching onto ashoulder 168 (FIG. 2) of the fishing neck 152. The body 156 carries amember 170 positioned relative to the shoulders 164, 166 for engagingand depressing the sleeve 136 from the position shown in FIG. lA.to theposition shown in FIG'. 2 in response to latching of the overshot 154onto the fishing neck 152.

A spring 172 biases the arms 1'58, 160 toward 'a latched position forsnapping about the shoulder 168. It will be seen that the inclinedsurface 174 on the fishing neck 152 acts to spread the arms 158, 160preparatory to latching onto the shoulder 168. For sealing against theinside of the drill string 20 the body 156 carries a washer 176capivated by a nut 178. The upper end of the overshot 154 includes a cap180 having a spear point or fishing neck 182 thereon for purposes morefully explained hereinafter.

After the overshot 154 is placed inside the drill string 20, acirculating head and tube catcher adapted to latch onto the fishing neck182 are attached to the joint of drill pipe exposed at the drillingmachine. Drilling fluid is then pumped into the drill string 20 whichacts against the washer 176 to move the overshot 154 through the drillstring 20 toward the bit 22. Drilling fluid captivated in the drillstring between the washers 148, 176 moves through the passages 134, 132,138 in the manner suggested by the arrows 140, 142.

As the overshot 154 reaches the fishing neck 152, the member 170 engagesthe sleeve 136 and moves the same toward the bit end of the drill stringfromthe position illustrated in FIG. 1A to the position illustrated inFIG. 2. As the member 170 abuts the top of the fishing neck 152, theshouldersl64, 166 of the latch arms 158,

I60 engage'under the shoulder 168 to positively mechanically hold thesleeve 136 in the position illustrated in FIG. 2. It is apparent'thatmovement of the sleeve 136 toward the bit end of the drill string'20effects movement ofthe member 106 toward the position illustrated inFIG. 2. Consequently, the valve body 130 moves so that the passages132,138 are no longer in registry. Thus,fluid communication across thesealing washer 148 is interrupted. Contemporaneously, the camming member126 engages the projections 100 of the latch elements 80, 82 therebyretracting thesame out of engagement with the shoulder 96'provided bythe landing nipple 14. It is accordingly apparent that the core tube 24is free for movementin thedrill string 20 away from the bit end thereof.

When drilling an up, down or horizontal hole,'the circulation ofdrilling fluidrri ay bereversed in'a conventional manner top'um'p downthe annulus between the drill string 20 and the bore hole. Consequently,fluid enters the drill string 20 at the bit end thereof and flowsupwardly in the drill'string' Because of the reactive surfaces exposedto the pressures of reverse circulation such as-the ,wallthicknessoftheshelli74 and the shoulder of the washer 148, the core tube2 4 ispumped out of the drill string2 0. As the core tube 2 4'rea ches thedrilling machine, it is retained by the tube catcher forsubsequentmemovalf i -""l'he device of this invention providesseveraldesirableua-dvantages. First, the latch 76 is positivelymechanically held in both the latched arid uiilatched posi-' I tions anddoes not depend on fluid p're'ssure'diffeientials to maintain the latchmechanism in either of its positions.

Second the valve particularly insensitive to erosion from drilling fluidand/or cuttings; When the provided by the exterior of the valve body andthe interior of the tubular shell 74. Thus, the sealing sur-- faces arenot themselves subject to erosion from drilling. fluid during drillings.In the collapsed or movable configuration of the core tube 24, asillustrated in FIG. 2, the interiorsurface of the tubular shell 74 isexposed to drilling fluid. It will be apparent, howeverfthat thedrilling fluid does not-flow through the shell 74 during retrieval ofthe core tube 24. It will also be apparent that the position of thepassage 138 may be adjusted slightly so that it is closed by the upperportion of the valve body 130 during retrieval ofithe core tube 24 sothat the sealing surfaces are not exposed todrilling fluid during eitherconfiguration of the core tube 24.

Third, the overshot 154 at the core tube latched thereto can beretrieved from inside the drill string ei- .ther by .reversecirculation, as mentioned previouslymr by wireline. In the latterevent,- a wi'reline maybe at-- tached by a pull-out socket to the neck182 before pumping the overshot 154into thedrill string 20. In thealternative a separate wireline retrievableovershot may be placed intothe drill string 20 to retrieve the overshot 1'54 and core tube 24attached thereto.

I claim:

.1. A coring tool for attachment to a hollow drill stringhavingithe-reon an annular bit operative inside a bore hole, the toolcomprising an elongate pumpable core tube,;mounted for movement betweena first position in core receiving relation to the bit and a secondposition spaced axially along the drill string from the first Iposition, the tube comprising:

means for sealing between the tube exterior and the drill stringinterior for driving the tube toward the a first element on the memberoperative in the first position thereof for engaging the latch andholding the same in the latched position; and

a second element on the member operative in the second position thereoffor engaging the latch and holding the same in the unlatched position;and

means for moving the member beween the first and second positionsthereof including means normally biasing the member toward the firstposition thereof; and

means pumpable down the drill string for securement to the core tube formoving the member to the second position thereof upon securement to thecore tube.

2. The coring tool of claim 1 wherein the core tube includes a tubularshell housing the latch and the member.

3. The core tube of claim 2 further comprising means for allowingcirculation of drilling fluid through the drill string past a sealingmeans when the latch is in the latched position thereof, the circulationallowing means including a valve body, inside the shell, carried by themember for reciprocable movement and defining the first passage openingthrough the side thereof;

a sleeve rigid with the valve body extending longitudinally of the coretube, and spanning the sealing means, the sleeve providing a secondpassage communicating at one end thereof with the first passage andopening at the other end thereof exteriorly of the core tube; and

the tubular shell providing therethrough a third passage registeringwith the first passage in the first position of the member.

4. The core tube of claim 3 wherein the circulation allowing meansincludes means for preventing circulation of drilling fluid through thedrill string past the sealing means when the latch is in the unlatchedposition, the circulation preventing means including means for movingthe valve body relative to the tubular shell and misaligning the firstand third passages contemporaneously with movement of the member awayfrom the first position toward the second position.

5. The core tube of claim 4 further comprising a coupling memberattached to one end of the tubular shell providing an openingtherethrough receiving the sleeve. the sleeve extending beyond the endof the coupling member in the first position of the actuating member.

6. The core tube of claim 5 wherein the coupling member includes afishing neck thereon.

7. The core tube of claim 6 wherein the securement means comprises meansfor attachment to the fishing neck.

8. A core drilling tool for attachment to a hollow drill stringcomprising an elongate pumpable core tube mounted for movement between afirst location for receiving a core and a second location spaced axiallyalong the drill string from the first location, the tube comprising acore receiving end and an other end; means for sealing intermediate thetwo ends between the tube exterior and the drill string interior; alatch movable between a latched position for securing the tube at thefirst location to the drill string and an unlatched position freeing thetube for movement through the drill string;

means for holding the latch in the latched position and for holding thelatch in the unlatched position, the holding means including anactuating member extending longitudinally of the core tube and mountedfor reciprocable movement between first and second positionscorresponding respectively to the latch and unlatched positions of thelatch;

means biasing the actuating member toward the first position thereof;

means for allowing circulation of drilling fluid through the drillstring past the sealing means when the latch is in the latched positionthereof and preventing circulation of drilling fluid through the drillstring past the sealing means when the latch is in the unlatchedposition thereof, the circulation means comprising a valve body, rigidwith the actuating member, in-

cluding a first passage opening through the side thereof and a sleeveconnected to the valve body providing a second passage communicating atone end thereof with the first passage and opening at the other endthereof exteriorly of the core tube at a location away from the sealingmeans toward the other end of the core tube;

the core tube providing a third passage opening exteriorly of the coretube at a location between the sealing means and the core receiving end,aligned with the first passage in the first position of the actuatingmember for allowing fluid travel past the sealing means in the firstposition of the actuating member and misaligned with the first passagein the second position of the actuating member for preventing fluidtravel past the sealing means in the second position of the actuatingmember; and

means pumpable through the drill string for securement to the other endof the core tube; and

means carried by the pumpable means for moving the sleeve and theactuating member to the second position thereof in response tosecurement of the pumpable means to the core tube and for holding thesleeve and the actuating member in the second position thereof duringsecurement of the pumpable means to the core tube.

9. A coring tool for attachment to a hollow drill string, the toolcomprising an elongate pumpable core tube, mounted for movement betweena first position in core receiving relation to a bit and a secondposition spaced axially along the drill string from the first position,the tube comprising:

means for sealing between the exterior of the tube and the drill stringfor driving the tube toward the bit upon application of pressure theretothrough the drill string;

a latch movable between a latched position for securing the tube at thefirst position to the drill string and an unlatched position freeing thetube for movement;

means for holding the latch in the latched position and for holding thelatch in the unlatched position including an actuating member extendinglongitudinally of the core tube;

means reciprocably mounting the member between first and secondpositions corresponding respectively to the latched and unlatchedpositions;

a first element on the member operative in the first position thereoffor engaging the latch and holding the same in the latched position; and

a second element on the member operative in the second position thereoffor engaging the latch and holding the same in the unlatched position;

means for moving the member between the first and second positionsthereof including means normally biasing the member toward the firstposition thereof; and

means pumpable down the drill string for securement to the core tube forholding the member in the second position thereof upon securement to thecore tube;

means for allowing circulation of the drilling fluid through the drillstring past the sealing means when the latch is in the latched positionthereof and for preventing circulation of drilling fluid through thedrill string past the sealing means thereof when the latch is in theunlatched position thereof, the circulation means including a valvebody, inside the shell, carried by the member for reciprocable movementtherewith and defining a first passage opening through the side thereof;

a sleeve rigid with the valve body, extending longitudinally of the coretube and spanning the sealing means, the sleeve providing a secondpassage communicating at one end thereof with the first passage andopening at the other end thereof exteriorly of the core tube;

a tubular shell providing therethrough a third passage registering withthe first passage in the first position of the actuating member; and thesleeve being positioned exteriorly of the core tube for engagement withthe securement means for moving the valve body relative to the tubularshell and misaligning the first and third passages contemporaneouslywith movement of the actuating member away from the first positiontoward the second position thereof.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO.3,874,466 DATED April 1, 1975 INVENTOR(S) 1 Emory Eugene Fulford It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

In column 7, line 20 of claim 3, "a" should read -the.

In column 7, line 24 of claim 3, "the" should read a. r

In column 8, line 9 of claim 8, "latch" should read -latched.

Signed and sealed this 20th day of May 1975.

(SEAL) Attest:

C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officerand Trademarks

1. A coring tool for attachment to a hollow drill string having thereonan annular bit operative inside a bore hole, the tool comprising anelongate pumpable core tube, mounted for movement between a firstposition in core receiving relation to the bit and a second positionspaced axially along the drill string from the first position, the tubecomprising: means for sealing between the tube exterior and the drillstring interior for driving the tube toward the bit upon application ofpressure thereto through the drill string; a latch movable between alatched position for securing the tube at the first position to thedrill string and an unlatched position freeing the tube for movementthrough the drill string; means for holding the latch in the latchedposition and for holding the latch in the unlatched position, theholding means including an actuating member extending longitudinally ofthe core tube; means reciprocably mounting the member between first andsecond positions; a first element on the member operative in the firstposition thereof for engaging the latch and holding the same in thelatched position; and a second element on the member operative in thesecond position thereof for engaging the latch and holding the same inthe unlatched position; and means for moving the member beween the firstand second positions thereof including means normally biasing the membertoward the first position thereof; and means pumpable down the drillstring for securement to the core tube for moving the member to thesecond position thereof upon securement to the core tube.
 2. The coringtool of claim 1 wherein the core tube includes a tubular shell housingthe latch and the member.
 3. The core tube of claim 2 further comprisingmeans for allowing circulation of drilling fluid through the drillstring past a sealing means when the latch is in the latched positionthereof, the circulation allowing means including a valve body, insidethe shell, carried by the member for reciprocable movement and definingthe first passage opening through the side thereof; a sleeve rigid withthe valve body extending longitudinally of the core tube, and spanningthe sealing means, the sleeve providing a second passage communicatingat one end thereof with the first passage and opening at the other endthereof exteriorly of the core tube; and the tubular shell providingtherethrough a third passage registering with the first passage in thefirst position of the member.
 4. The core tube of claim 3 wherein thecirculation allowing means includes means for preventing circulation ofdrilling fluid through the drill string past the sealing means when thelatch is in the unlatched position, the circulation preventing meansincluding means for moving the valve body relative to the tubular shelland misaligning the first and third passages contemporaneously withmovement of the member away from the first position toward the secondposition.
 5. The core tube of claim 4 further comprising a couplIngmember attached to one end of the tubular shell providing an openingtherethrough receiving the sleeve, the sleeve extending beyond the endof the coupling member in the first position of the actuating member. 6.The core tube of claim 5 wherein the coupling member includes a fishingneck thereon.
 7. The core tube of claim 6 wherein the securement meanscomprises means for attachment to the fishing neck.
 8. A core drillingtool for attachment to a hollow drill string comprising an elongatepumpable core tube mounted for movement between a first location forreceiving a core and a second location spaced axially along the drillstring from the first location, the tube comprising a core receiving endand an other end; means for sealing intermediate the two ends betweenthe tube exterior and the drill string interior; a latch movable betweena latched position for securing the tube at the first location to thedrill string and an unlatched position freeing the tube for movementthrough the drill string; means for holding the latch in the latchedposition and for holding the latch in the unlatched position, theholding means including an actuating member extending longitudinally ofthe core tube and mounted for reciprocable movement between first andsecond positions corresponding respectively to the latch and unlatchedpositions of the latch; means biasing the actuating member toward thefirst position thereof; means for allowing circulation of drilling fluidthrough the drill string past the sealing means when the latch is in thelatched position thereof and preventing circulation of drilling fluidthrough the drill string past the sealing means when the latch is in theunlatched position thereof, the circulation means comprising a valvebody, rigid with the actuating member, including a first passage openingthrough the side thereof and a sleeve connected to the valve bodyproviding a second passage communicating at one end thereof with thefirst passage and opening at the other end thereof exteriorly of thecore tube at a location away from the sealing means toward the other endof the core tube; the core tube providing a third passage openingexteriorly of the core tube at a location between the sealing means andthe core receiving end, aligned with the first passage in the firstposition of the actuating member for allowing fluid travel past thesealing means in the first position of the actuating member andmisaligned with the first passage in the second position of theactuating member for preventing fluid travel past the sealing means inthe second position of the actuating member; and means pumpable throughthe drill string for securement to the other end of the core tube; andmeans carried by the pumpable means for moving the sleeve and theactuating member to the second position thereof in response tosecurement of the pumpable means to the core tube and for holding thesleeve and the actuating member in the second position thereof duringsecurement of the pumpable means to the core tube.
 9. A coring tool forattachment to a hollow drill string, the tool comprising an elongatepumpable core tube, mounted for movement between a first position incore receiving relation to a bit and a second position spaced axiallyalong the drill string from the first position, the tube comprising:means for sealing between the exterior of the tube and the drill stringfor driving the tube toward the bit upon application of pressure theretothrough the drill string; a latch movable between a latched position forsecuring the tube at the first position to the drill string and anunlatched position freeing the tube for movement; means for holding thelatch in the latched position and for holding the latch in the unlatchedposition including an actuating member extending longitudinally of thecore tube; means reciprocably mounting the member between first andsecond positions corresponding respectively to The latched and unlatchedpositions; a first element on the member operative in the first positionthereof for engaging the latch and holding the same in the latchedposition; and a second element on the member operative in the secondposition thereof for engaging the latch and holding the same in theunlatched position; means for moving the member between the first andsecond positions thereof including means normally biasing the membertoward the first position thereof; and means pumpable down the drillstring for securement to the core tube for holding the member in thesecond position thereof upon securement to the core tube; means forallowing circulation of the drilling fluid through the drill string pastthe sealing means when the latch is in the latched position thereof andfor preventing circulation of drilling fluid through the drill stringpast the sealing means thereof when the latch is in the unlatchedposition thereof, the circulation means including a valve body, insidethe shell, carried by the member for reciprocable movement therewith anddefining a first passage opening through the side thereof; a sleeverigid with the valve body, extending longitudinally of the core tube andspanning the sealing means, the sleeve providing a second passagecommunicating at one end thereof with the first passage and opening atthe other end thereof exteriorly of the core tube; a tubular shellproviding therethrough a third passage registering with the firstpassage in the first position of the actuating member; and the sleevebeing positioned exteriorly of the core tube for engagement with thesecurement means for moving the valve body relative to the tubular shelland misaligning the first and third passages contemporaneously withmovement of the actuating member away from the first position toward thesecond position thereof.